Synthesis of 5-vinylcyclohexa-1,3-diene

ABSTRACT

At least one alkyne compound is reacted with butadiene, piperylene and/or isoprene in the presence of the reaction product obtained by reducing a nickel(II) compound in the presence of at least one ligand material having the formula R3Z wherein Z is phosphorus or arsenic, and each R is an alkyl radical having from 1 to 12 carbon atoms with no branching nearer the Z than the second carbon atom. In a specific embodiment butadiene and acetylene are reacted in the presence of nickel(0) and tri-n-alkylphosphine to produce 5-vinylcyclohexa-1,3-diene and benzene.

Wnfite tates Patent [1 1 Fahey Dec. 24, 11974 SYNTHESIS OF 3,249,641 5/1966 Storrs Ct 21L... 260/666 B 5 Y 0 3 3,271,468 9/1966 Wilke et al. 260/668 3,586,727 6/1971 Wilke ct al 260/666 B Inventor: Darryl R. y, Bartlesvllle, k 3,629,347 12/1911 Wilke et 61 2611/666 1; [73] Assignee: Phillips Petroleum Company, 4

Bartksville, Ok]a Przmary Examiner-Delbert E. Gantz [22] F1 d J 11 1974 Assistant Examiner\ eronica OKccfc 1 e an.

[21] Appl. N0.: 432,442 [57] ABSTRACT Related Application Data At least one alkyne compound is reacted with butadi- [63] Continuation of Ser No 209 442 Dec 17 {97] ene, plperylene and/or isoprene in the presence of the abandoned reaction product obtained by reducing a nickel(ll) compound in the presence of at least one ligand mate- [52] U S. Cl 260/666 A 260/668 rial having the formula R Z wherein Z is phosphorus [51] i (507: 3/10 or arsenic, and each R is an alkyl radical having from [58] Field ''g l' 'fi B 668 l to 12 carbon atoms with no branching nearer the Z than the second carbon atom. In a specific embodihe res- [56] References Cited ment butadlene and acetylene are reacted 1n t p ence of n1ckel(0) and tr1-n-alkylphosph1ne to produce UNITED STATES PATENTS 5-vinylcyclohexa-l,3-diene and benzene. 2,686,208 8/1954 Reed 260/666 B 2,686,209 8/1954 R666 260 666 B 10 Clalms, N0 Drawings dichlorobis( triethylphosphine )nickel(l1),

This is a continuation of copending application Ser. No. 209,442, filed Dec. 17, 1971, now abandoned.

This invention relates to a new and improved process for reacting at least one alkyne compound with butadiene, piperylene and/or isoprene. in one aspect the invention relates to a new catalyst for the reaction of an alkyne with butadiene or methyl derivative thereof to provide a high yield of a -vinylcyclohexa-l,3-diene type compound.

Accordingly, it is an object of the present invention to provide a new and improved process for the reaction of an alkyne with butadiene or methyl derivative thereof to produce 5-vinylcyclohexa-l,3-diene compounds. Another object of the invention is to increase the yield of 5-vinylcyclohexa-l,3-diene compounds.

Other objects, aspects and advantages of the invention will be apparent from a study of the specification and the appended claims to the invention.

The conjugated diolefins which can be utilized in the present process include butadiene, piperylene, isoprene, and admixtures thereof. The alkyne compounds which are useful in the present process have the structure RC ECR, wherein each R is individually selected from the group consisting of hydrogen, alkyl and fluoroalkyl having 1 to carbon atoms, cycloalkyl having 3 to 8 carbon atoms, aryl and alkaryl having from 6 to 10 carbon atoms, -ROR" wherein R is alkylene having from 1 to 4 carbon atoms and R" is alkyl having from 1 to 4 carbon atoms, and (for use in the absence of an organometallic or metal hydride reducing agent, vide infra) -CO-O-R" wherein R is as defined above, and combinations thereof, the number of carbon atoms in any R group being less than 1 l and the total number of carbon atoms in the molecule being less than 15. Exemplary alkyne compounds include acetylene, propyne, l-butyne, 2-butyne, 2- pentyne, l-hexyne, 2-methylhex-3-yne, l-octyne, 1- decyne, 2-tetradecyne, cy'clopropylacetylene, cyclohexylacetylene, cyclooctylacetylene, phenylacetylene, diphenylacetylene, p-butylphenylacetylene, 4- fluorohex-l-yne, 4-oxapent-l-yne, 5-oxanon-1-yne, 7- oxadec-l-yne, dimethylacetylenedicarboxylate, isobutyl acetylenecarboxylate, and combinations thereof. The mole ratio of the conjugated diolefm to the alkyne compound will generally be in the range of about 0.1 to about 20, preferably in the range of about 0.5 to about 4. v

The nickel(ll) compound can be selected from those nickel(II) compounds reducible by organometallic and metal hydride reducing agents or by the novel thermal process of the instant invention. Additionally, the anion should not have any significant adverse effect upon the reaction of the nickel(II) compound with the trialkylphosphine or the trialkylarsine or upon the reaction of the conjugated diolefln with the alkyne compound. Exemplary nickel(II) compounds which are suitable include nickel chloride, nickel bromide, nickel acetate, nickel iodide, nickel propionate, nickel cyanide, nickel benzoate, nickel naphthenate, nickel oxalate, nickel acetylacetonate, nickel benzoylacetonate, transbromo- (o-tolyl)bis(triethylphosphine)nickel(ll), transtransbromo(pentaflu 0rophenyl)bis(triphenylphosphine)- nickel(ll), trans-chloro(2,5- dichlorophenyl)bis(triethylphosphine)nickel(ll), tran- 2 s-chloro(trifluorovinyl)bis(triphenylphosphine)nickel- (II), trans-dibromobis(triethylphosphine)nickel(ll), trans-diiodobis(tri-n-butylarsine)nickel(ll), and combinations thereof.

The ligand materials which are suitable for utilization in the present process have the formula RIIISZ wherein Z is selected from the group consisting of phosphorus and arsenic, and wherein each R' is individually selected from the group consisting of alkyl radicals having from 1 to 12 carbon atoms and no branching nearer the Z than the second carbon atom. Exemplary suitable ligand materials include trimethylphoscombinations thereof. The nickel(II) compound and the ligand can be added as separate components or the ligand can be present as part of the nickel(ll) compound.

The ratio of the gram atoms of nickel to the moles of alkyne compound will be at least sufficient to achieve a significant catalytic effect, and will generally be in the range of about 0.0001 to about 1, and preferably in the range of about 0.001 to about 0.2. The ratio of moles of the ligand to the gram atoms of nickel will be at least sufficient to achieve a significant effect from the addition of the ligand, and will generally be in the range of about 0.01 to about 20, preferably in the range of about 1 to about 8.

The reduction of the nickel(II) compound in the presence of the ligand can be accomplished by any suitable method known in the art. In one embodiment of the present invention the reduction of the nickel is effected, at least in part, by the presence of at least one suitable organometallic reducing agent or metal hydride reducing agent. These reducing agents include compounds of elements of Groups IA, IIA, lIB and 111A of the Periodic Table of the Elements set forth on page B2 of the Handbook'of Chemistry and Physics, Chemical Rubber Co., 45th Edition, 1964. The compounds of lithium, sodium, potassium, magnesium, calcium, boron, and aluminum are presently preferred because of the greater availability at reasonable cost. Examples of suitable reducing agents include lithium hydride, sodium hydride, lithium aluminum hydride, sodium borohydride, calcium hydride, aluminum hydride, phenylsodium, phenyllithium, benzyl potassium, phenylmagnesium chloride, ethylmagnesium bromide, triethylaluminum, diisobutylaluminum hydride, diethylethoxyaluminum, phenylaluminum sesquichloride, diethylaluminum chloride, beryllium diethyl, magnesium diethyl, diborane, triethyl boron, diethyl zinc, and diethyl cadmium, and admixtures thereof.

When the reduction of the valence of the nickel is effected in the presence of an organometallic reducing agent or a metal hydride reducing agent, the amount of the organometallic reducing agent or metal hydride reducing agent employed will be at least sufficient to achieve the desired reduction. The mole ratio of reducing agent to nickel(ll) compound will generally be in the range of about 2 to about 20, more preferably in the range of about 2 to about 8.

It has also been found that the reduction of the valence of the nickel can be effected in the presence of the conjugated diolefin and the alkyne compound, in the absence of an organometallic reducing agent or a metal hydride reducing agent, by heating the admixture to a temperature in the range of about 50 C to about 120 C, preferably in the range of about 60 C to about 100 C. The exact mechanism by which the reduction takes place under these conditions is not known with certainty, but it is thought possible that part of the alkyne feed acts as a reducing agent.

It has further been found that the valence of the nickel can be reduced in the presence of the conjugated diolefin, the alkyne compound and methanol and in the absence of an organometallic reducing agent or a metal hydride reducing agent. Again, the exact mechanism of the reduction is not known with certainty, and the presence of the methanol in the initial reactants has the apparent effect of increasing the ratio of benzene to S-vinylcyClohexa-l ,3-diene produced in the reaction of acetylene and butadiene. When methanol is employed, the mole ratio of methanol to nickel(ll) compound will generally be in the range of about 1 to about 150, more preferably in the range of about 50 to about 100.

The nickel()-ligand catalyst can be formed in situ in the presence of the conjugated diolefin and the alkyne compound, or the catalyst can be preformed prior to contact with the conjugated diolefin and the alkyne compound.

If desired, a suitable solvent or diluent can be employed as the media for the reductionof the nickel valence and/or for the reaction of the conjugated diolefin and the alkyne compound. Exemplary solvents or diluents include benzene, toluene, cyclohexane, cumene, isoctane, methanol, ethyl acetate, acetone, di-n-butyl ether, and admixtures thereof. The solvent or diluent should not have significant potential for reacting with the catalyst components or with one of the feed components at the conditions under which the solvent is being utilized.

The reduction of the nickel catalyst and the oligomerization reaction can be effected at any suitable temperature and pressure. Generally the temperature for the reduction of the nickel in the presence of an organometallic or metal hydride reducing agent will be in the range of about 78 C to about 50 C, preferably in the range of about 78 C to about 0 C. When an organometallic reducing agent or metal hydride reducing agent is employed in the reduction of the nickel, the temperature for the oligomerization reaction will usually be in the range of about 1 5 C to about 100 C, and preferably in the range of about 0 C to about 30 C. A temperature in the range of about 50 C to about 120 C can be employed for both reactions when carried out in the absence of either an organometallic reducing agent or a metal hydride reducing agent, with the temperature range of about 60 C to about 100 C being presently preferred for both reactions. The pressure for both the reduction and the oligomerization will normally be in the range of about 5 to about 150 psig.

The desirable reaction time is a function of other variables, such as temperature, concentration, catalyst level, etc. In general, in a batch reaction, it is desirable to carry out the oligomerization reaction until no further significant pressure drop occurs, normally requiring about 0.5 to about 50 hours.

In a preferred embodiment of the present invention, the primary product of the oligomerization reaction is a 5-vinylcyclohexa-l,B-diene compound represented by the structure wherein each R is as defined hereinabove with respect to the alkyne compound, and each R is hydrogen or methyl with at least two of the Rs being hydrogen. In presently preferred embodiments, at least 50 mole percent, and more preferably at least 60 mole percent, of the alkyne will be converted to this product. Other valuable products can also be produced in yields which are commercially significant. For example, in the reaction of butadiene and acetylene, significant amounts of benzene can be produced.

The following examples are presented in further illustration of the invention, but should not be construed in undue limitation thereof. In each run of the examples, the reactions were carried out under a nitrogen atmosphere with anhydrous reagents and in dry, deoxygenated solvent. Phillips pure grade butadiene was used as the diolefin. The acetylene employed in the runs had been passed through two 78 C traps to remove any acetone. The acetylene-butadiene reactions were conducted in a thick-walled glass bottle of 3 oz. capacity fitted with a stainless steel cap and sealed by a neoprene rubber O-ring. Each cap was fitted with a pressure gauge, a gas inlet-outlet port, and a vertical tubular serum-stoppered port encompassing a ball type stopcock through which a syringe needle could be passed.

EXAMPLE I In each of the following series of runs 0.10 g (0.39 mmol) of nickel acetylacetonate, 10.0 ml of cyclohexane, and the desired quantity of a tert-phosphine, if used, were added to a previously dried reaction bottle. The bottle was then capped, flushed with nitrogen, partially evacuated, and cooled to about 78 C. Then 10.8 g (200 mmol) of butadiene and 1.3 g (50 mmol) of acetylene were introduced into the bottle, followed by 0.80 ml of 25 wt. percent triethylaluminum in cyclohexane, by syringe through the vertical port. Then the ball valve was closed, and the mixture was warmed to 25 C and magnetically stirred until the pressure dropped from the initial value of about psig to less than 15 psig. The unreacted gases were vented, and the crude, liquid product mixture, spiked with ethylbenzene as a standard, was analyzed by gas liquid partition chromatography isothermally at C and at C. The results are reported in the following table:

6 TABLE I PRODUCTS Yield in Yield Based on Acetylene Yield Based on Butadiene Grams Of LzNi B:A Temp. Time VCHD COT BZ STy VCH COD Other Products Run Ligand (a) (b) C Hr. (c) (d) (e) (f) (g) (h) (i) 1 None None 4 25 42 4 1 1 1 0.01

4 Mono, 2 4 25 17 1 1 1 1 1 0.01

5 Poi-Bu), 1 4 25 16 61 1 22 1 1 0.06

6 P(nBu) 4 4 25 6 66 1 1 1 0.06

7 Poi-Bu), 8 4 22 41 1 12 1 1 0.01

8 P(n-BU) 2 1 25 3 56 1 22 1 1 0.32

' A dash indicates that the presence ofthis component was not detected.

(:1) Ratio of moles of ligand to gram atoms of nickel.

(b) Mole ratio of butadiene 1o acetylene.

(c) S-Vinylcyclohexa-l.3-diene.

(d) 1.3.6-Cyclooctattien.

(e) Benzene.

(g) 4-Vi1iy1cyclohexene.

(h) 1.5-Cyclooctadiene.

(1) Products detected by gas liquid partitionchromatography. m "N In run 1-, the absence of a ligand is accompanied by ml of cyclohexane was syringed into the bottle, and the low yields. In run 3, the reaction is relatively slow in the ball stopcock was closed. Then 12.7 g (235 mmol) of presence of a triarylphos'phine ligand. In run 4, the butadiene and 1.5 g 5 8 mmol) of acetylene were presence of a phosphite ligand is accompanied by low added, the bottle was warmed to 25, and the reaction yields. Runs 2, 5, 6, 7 and 8 demonstrate the high yields 2 5 was carried out for 4 hours at 25 C. The reaction soluachievable in accordance with the present invention. tion was analyzed as in Example I. The results are as 4-Viny1cyc1ohexene, benzene, 1,5-cyc1ooctadiene, and follows: styrene were identified by comparison of glpc retention TABLE H times with those of authentic samples and by comblnat on glpc-mass spectral ana1ys1s. 5-V1ny1cyc1ohexa-1,3- 3Q Yield Based Yield Based diene and 1,3,6-cyclooctatr1ene were 1solated by prepmduct n Acetylene on Butadiene parative gas liquid partition chromatography and were -v 1 111 -l,3-d 52 1dent1f1ed from then mass and nrnr spectra. 5-\ 1ny lcyi gf af g gf 1 clohexa-1,3-d1ene could also be isolated by d1st1llat1on: Benzene 18 p o o (90 mm) 4-Viny1cyclohexene 1 As shown in Table I, the highest selectivity to 5-vinylcyc1ohexa-1,3-diene occurs with tri-nallrylphosphines at R PzNi mole ratios between 1:1 and EXAMPLE In 4:1. At low butadiene to acetylene mole rat1os, reaction In each of the following runs, a predried pressure bottimes are shortened and reaction temperatures below 1 was h d i h cyclohexane, h i k lfll) 25 may be used, but the select1v1ty to 5-v1ny1cycloheX- pound (if any), a tert-phosphine (if any), l-2 ml of a-1,3-diene suffers and the benzene y1eld 1ncreases. h l (if b di d acetylene as i E ample I. As the mixture was stirred, its temperature was EXAMPLE. increased (the bottle was immersed in a heated oil A predried pressure bottl was charg d Wlth 010 g bath) until the system pressure began to decrease. mmol) of 1ene)nlckelw) and After no further reaction was apparent, the reaction sopp in a y After Partially evacuatmg the P lution was cooled and then analyzed as in Example I. and Cooling it to mmol of 0 Results are reported in the following table:

' TABLE 111 Run 1 2 3 4 5 Nickel compound (Et P),Ni(o-to|yl)Br nickel nickel (Et P) NiCl None acetylacetonate acetylacetonate 1 Amount. mmol 1.1 0.39 0.39 0.274 Ligand See above P(n-Bu);,

Ptn-Bu); See above F(n-Bu) Amount, mmol 0.77 0.77 1.09 Butadiene, mmol 200 200 200 200 200 Acetylene, mmol 50 50 50 50 Methanol, ml 1.5 2.0 None 2.0 None Reaction Temperature, C 50 80 Reaction Time, hr. 18 16 6 44 5 Products (1) 71 Yield based on Acetylene 5-Vinylcyc1ohexa-1,3-diene 27 50 45 '15 1.3.6-Cyclooctatriene 1 1 1 1 Benzene 17 32 10 12 0.5

Styrene 2 4 1 ND (2) 71 Yield Based on Butadiene 4-Vinylcyclohexene 1 ND' 1 ND 0.5

A dash indicates that the presence 01 this compound was not detected. P(n-l3u); is tri-n-butylphosphine. ND indicates the yield of this compound was not determined.

Reasonable variations and modifications are possible within the scope of the foregoing disclosure and the appended claimsto the invention.

That which is claimed is:

l. A method for producing S-vinylcyclohexa-l ,3- diene which comprises reacting under suitable reaction conditions reactants consisting essentially of butadieneand acetylene in contact with a catalyst selected from the group consisting of:

a. a reaction product obtained by the reduction of a nickel(II) compound in contact with a ligand having the formula R 2 wherein Z is selected from the group consisting of phosphorus and arsenic, and each R is individually selected from the group consisting of alkyl radicals having from 1 to 12 carbon atoms and no branching nearer the Z than the second carbon atom, said nickel(ll) compound being selected from the group consisting of nickel ch1oride, nickel bromide, nickel acetate, nickel iodide, nickel propionate, nickel cyanide, nickel benzoate, nickel naphthenate, nickel oxalate, nickel acetylacetonate, nickel benzoylacetonate, and combinations thereof;

. a mixture of bis( 1 ,S-cyclooctadiene)nickel() and tri-n-butyl phosphine; and

c. a reaction product obtained by the reduction of a nickel(ll) complex selected from the group consisting of trans-bromo(o-tolyl)bis(triethylphosphine)- nickel(Il), trans-dichlorobis(triethylphosphine)- nickel(II), trans-chloro(2,5- dichlorophenyl)bis(triethylphosphine)nickel(ll), trans-dibromobis(triethylphosphine)nickel(ll), tr-

, ans-diiodobis(tri-n-butylarsine)nickel(ll), and

combinations thereof;

to produce S-vinylcyclohexa-l,3-diene as a principal product of the reaction.

2. A method in accordance with claim 1 wherein said catalyst is the reaction product obtained by the reduction of nickel acetylacetonate in contact with a ligand selected from the group consisting of triethyl phosphine and tri-n-butyl phosphine.

3. A method in accordance with claim 2 wherein the reduction is accomplished by the addition of an organometallic reducing agent.

4. A method in accordance with claim 3 wherein said reaction conditions comprise a temperature in the range of about 0 C to about 30 C. I

5. A method in accordancewith claim 1 wherein said catalyst is a mixtureof bis(l,5- cyclooctadiene)nickel(0) and tri n-butyl phosphine.

6. A method in accordance with claim 5 wherein said reaction conditions comprise a temperature in the range of about 0 C to about 30 C.

7. A method in accordance with claim 1 wherein said catalyst is the reaction product obtained by the reduction of trans-bromo(o-tolyl)bis(triethylphosphine)- nickel(II).

8. A method in accordance with claim 7 wherein the reduction is accomplished by heating the nickel complex in the presence of butadiene, acetylene, and methanol to a temperature in the range of about 50 C to about C.

9. A method in accordance with claim 2 wherein the reduction is accomplished by heating the nickel compound in the presence of butadiene and acetylene to a temperature in the range of about 50 C to about 120 C.

10. A method in accordance with claim 1 wherein said catalyst is the reaction product obtained by the reduction of trans-dichlorobis(triethylphosphine)nickel- (II), and the reduction is accomplished by heating the nickel complex in the presence of butadiene and acetylene to a temperature in the range of about 50 C to about 120 C. 

1. A METHOD FOR PRODUCING 5-VINYCYCLOHEXA-1,3-DIENE WHICH COMPRISES REACTING UNDER SUITABLE REACTION CONDITIONS REACTANTS CONSISTING ESSENTIALLY OF BUTADIENE AND ACETYLENE IN CONTACT WITH A CATALYST SELECTED FROM THE GROUP CONSISTING OF: A. A REACTION PRODUCT OBTAINED BY THE REDUCTION OF A NICKEL(II) COMPOUND IN CONTACT WITH A LIGAND HAVING THE FORMULA R3Z WHEREIN Z IS SELECTED FROM THE GROUP CONSISTING OF PHOSPHORUS AND ARSENIC, AND EACH R IS INDIVIDUALLY SELECTED FROM GROUP CONSISTING OF ALKYL RADICALS HAVING FROM 1 TO 12 CARBON ATOMS AND NO BRANCHING NEARER THE Z THAN THE SECOND CARBON ATOM, SAID NICKEL(II) COMPOUND BEING SELECTED FROM THE GROUP CONSISTING OF NICKEL CHLORIDE, NICKEL BROMIDE, NICKEL ACETATE, NICKEL IODIDE, NICKEL PROPIONATE, NICKEL CYANIDE, NICKEL BENZOATE, NICKEL NAPHTHENATE, NICKEL OXALATE, NICKEL ACETYLACETONATE, NICKEL BENZOYLACETONATE, AND CONBINATIONS THEREOF, B. A MIXTURE OF BIS(1,5-CYCLOOCTADIENE)NICKEL(0) AND TRI-NBUTYL PHOSPHINE, AND C. A REACTION PRODUCT OBTAINED BY THE REDUCTION OF A NICKEL(II) COMPLEX SELECTED FROM THE GROUP CONSISTING OF TRANSBROMO(O-TOLYL)BIS(TRIETHYLPHOSPHINE)NICKEL(O) AND TRI-NDICHLOROBIS(TRIETHYLPHOSPHINE)NICKEL(II), TRANS-CHLORO(2,5DICHLOROPHENYL)BIS(TRIETHYLPHOSPHINE)NICKEL(II), TRANSDIBROMOBIS(TRIETHYLPHOSPHINE)NICKEL(II), TRANSDIIODOBIS(TRI-N-BUTYLARSINE(NICKEL(II), AND COMBINATIONS THEREOF; TO PRODUCE 5-VINYLCYCLOHEXA-1,3-DIENE AS A PRINCIPAL PRODUCT OF THE REACTION.
 2. A method in accordance with claim 1 wherein said catalyst is the reaction product obtained by the reduction of nickel acetylacetonate in contact with a ligand selected from the group consisting of triethyl phosphine and tri-n-butyl phosphine.
 3. A method in accordance with claim 2 wherein the reduction is accomplished by the addition of an organometallic reducing agent.
 4. A method in accordance with claim 3 wherein said reaction conditions comprise a temperature in the range of about 0* C to about 30* C.
 5. A method in accordance with claim 1 wherein said catalyst is a mixture of bis(1,5-cyclooctadiene)nickel(0) and tri-n-butyl phosphine.
 6. A method in accordance with claim 5 wherein said reaction conditions comprise a temperature in the range of about 0* C to about 30* C.
 7. A method in accordance with claim 1 wherein said catalyst is the reaction product obtained by the reduction of trans-bromo(o-tolyl)bis(triethylphosphine)nickel(II).
 8. A method in accordance with claim 7 wherein the reduction is accomplished by heating the nickel complex in the presence of butadiene, acetylene, and methanol to a temperature in the range of about 50* C to about 120* C.
 9. A method in accordance with claim 2 wherein the reduction is accomplished by heating the nickel compound in the presence of butadiene and acetylene to a temperature in the range of about 50* C to about 120* C.
 10. A method in accordance with claim 1 wherein said catalyst is the reaction product obtained by the reduction of trans-dichlorobis(triethylphosphine)nickel(II), and thE reduction is accomplished by heating the nickel complex in the presence of butadiene and acetylene to a temperature in the range of about 50* C to about 120* C. 